During a highway trip that was bumper to bumper traffic at approximately 15mph, the car suddenly would not accelerate while operating on gasoline (not electric). The engine revs would increase to maximum without movement from the car (as if the car was in neutral). After checking the gear lever to make sure it was still in D, tried to accelerate again and engine rev high without movement. Eventually car came to stop with brakes, and the car could move on electric power (in hybrid mode), pulled over and turned off the car to visually inspect. After not identifying anything, turned on car and operation resumed to normal and would accelerate on gas power.

- Los Angeles, CA, USA